Hitachi 670 Series Installation Manual page 67

1MRK514026-UUS Rev. P
Connecting the power supply module
The wiring from the cubicle terminal block to the REX060 unit (see figure
diagram) must be made in accordance with the established guidelines for this type of equipment. The
auxiliary power wiring should have a minimum cross-sectional area of 1.0 mm
250 V. Branch circuit protection must be provided in the auxiliary power supply wiring to the IED and, if
necessary, it must be possible to disconnect it manually from the power supply. Fuse or circuit breaker up
to 6 A and 250 V should be close to the equipment. It is recommended to separate the instrument
transformer leads from the other cables, that is, they should not be run in the same cable ducts or loom.
SIT Connections
• Low Voltage (LV) Terminals:
The low voltage terminals of SIT that provide 240 Vac shall be wired to REX060 and REX062
terminals. Available taps of the low voltage winding shall be connected in order to achieve the 240
Vac at the terminals of SIT. The low voltage terminal X4 in the connection diagram shall be
grounded.
• High Voltage (HV) Terminals:
The high voltage terminals of SIT are wired to the generator neutral and to the generator earth as
shown in the connection diagrams. Available taps of the high voltage winding shall be connected to
achieve the 100% of the primary rated voltage of SIT at its terminals. The high voltage terminal H2
in the connection diagram shall be grounded.
• Earthing:
The frame of SIT shall be grounded according to guidelines of standards that are applicable for
primary devices.
SIT Installation for Generator with ANSI Grounding (effective high resistance
earthing via a distribution transformer and secondary neutral grounding
resistor)
One resistor with value of 100 Ω and power at least 900 W shall be connected to the LV terminals of SIT.
For example, 4 pieces of aluminum housed resistor of with value 25 Ω and 250 W connected in series
and mounted on appropriate heat sink.
The purpose of this resistance is to damp abnormal voltages that can be related to Ferro resonance
phenomena.
MCB or fuse at the LV side of SIT
Either one MCB or one fuse shall be installed close to the terminals X1-X4 of SIT in the case of IEC
grounding or close to the terminals of the resistor for the ferroresonance reduction in the case of ANSI
grounding (the MCB or the fuse does not disconnect the resistor from the terminals of SIT).
A.1 MCB rated data
One 2 poles MCB shall be installed in the circuit that is connected to the LV terminals X1 and X4 of SIT.
The rated data of the MCB are listed below:
670 series
Installation manual
For connection details regarding REX060, REX061, REX062 and SIT refer to section
Connection diagrams in the REG670 Technical Manual.
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Section 6
Connecting
34 for PSM connection
2
and a voltage rating of
61